Various methods have been proposed for the production of para-xylene that is industrially very useful.
It is known that para-xylene is produced selectively when toluene is alkylated with methyl alcohol in the presence of a crystalline aluminosilicate catalyst containing fine pores having definite dimensions, such as ZSM-5 Zeolite.
It is also known that the selectivity of para-xylene is increased when sodium or hydrogen ions in the crystalline aluminosilicate catalyst are replaced by other metals. For example, Japanese patent application Laid-Open No. 7598/1980 discloses a process for the production of para-xylene from toluene and methyl alcohol and a process for the production of para-xylene by isomerization of ortho- or meta-xylene or disproportionation of toluene, using a catalyst comprising a siliceous support and a metal, such as chromium, beryllium, and titanium.
Conventional techniques, however, have disadvantages in that the selectivity of para-xylene is still insufficiently satisfactory and the catalytic activity drops in a relatively short period of time.